Oscillation generation



July 23, 1935 G. L.. USSELM AN 2,009,358

OSCILLATION GENERATION Filed June 27, 1930 2 Sheets-Sheet 1 ATTORNEY Patented July 23, 1935 PATENT! OFFICE OSCILLATION GENERATION George L. Usselman, Port Jefferson, N. Y., as

signor to Radio Corporation corporation of Delaware of America, a

Application June 27, 1930, Serial No. 464,250

45 Claims.

This invention appertains to the art of electricaloscillation generation and has for its main object the provision of new and useful methods and means for the generation of high frequency electrical oscillations.

It has been common in the past to generate relatively high frequency oscillations with 'an electron discharge device having an anode, a cathode, and a control electrode. A condition necessary to the generation of oscillations with.

such a device is that the control electrode or grid, and anode or plate, potentials exist each instant in phase opposition. It has been impossible to speed .up the electrons beyond a certain speed .by increasing the anode potential due to the fact that increase in anode potential beyond a certain point would result in the destruction of the vtube. Consequently the time lag required for electrons to travel from the cathode to the anode establishes an upper limit to frequencies generated. To obviate the foregoing difficulty and to obtain higher frequency oscillations than heretofore possible in an electron discharge device, is an object of the present invention and it is accomplished by utilizing the time lag of the electrons in traveling from a cathode to an anode for the generation of high frequency oscillations. More fully, to accomplish this object there is provided, according to the present invention, an anode, voltages on portions of which continuously fluctuate in a fashion such that when the voltage on a portion of the anode attracts electrons towards it, by the time the electrons reach that portion of the anode, the voltage has changed so that the electrons strike the anode at a time when the struck portion is at a lower potential.

To increase the time lag of the electrons traveling from cathode to anode in order to insure impinging of electrons at the proper time on the anode, is a further object of this invention and this object is fulfilled by lengthening the path of electron travel from cathode to anode by electrcstatically and/or electromagnetically deflecting and twisting electrons in their path from the cathode to the anode.

In order to have an anode in which, voltages across portions of which continuously vary at the desired'frequency, the anode, according to this invention, is preferably made in the form of a radiator one-half wave length long whose center portion is shielded from the electrons. In this manner the electrons cannot pass directly. from the filament to the anode but must strike it some distance from the center. By proper pro- Figures 1 and 2 are right angled views of an l0 oscillator built according to the present invention, the magnetic means for twisting electrons from the cathode to the anode being omitted for the sake of simplicity. v

Figure 3 is similar to Figure 1 having in addition, means for modulating and directionally transmitting the oscillations set up,

Figure 4 indicates, diagrammatically, another way of modulating the oscillations generated, and,

Figure 5 is a partial view of a preferred form of oscillator.

Referring to Figure 1 an anode A in the form of a radiator one-half wave length long, the wave length taken being that of a desired frequency,

is supported within an hermetically sealed envelope 0 which may be evacuated to any degree or filled with a suitable gas to any desired pressure. Anode potential is supplied through a lead D attached substantially to the center of the anode A which is the voltage nodal point of the anode during oscillation. About the lead D there is placed a cylindrical shield or member S physically and electrically connected with. a metallic cylindrical member or shield B coaxial with, and intermediate the ends of anode A, shielding the central portion of anode A from electrons from cathode C. Biasi ng potential for shield S and shield B is supplied through a lead F. In effect, shield B is a control electrode since it determines the path of the electrons from the cathode to the anode, and as will be seen later modulating potentials may be applied to this shield or control electrode. The shield diflers however from what is known as the conventional grid in that the shield or control electrode does not ordinarily stop the flow of electrons but only controls the path thereof.

The cathode, best seen in Figure 2, is placed in a plane traversing and preferably perpendicular to the axis of anode A and of sleeve B and is provided with leads Z, as shown, for suitable energization thereof. The cathode may be of any known type and suitably coated to increase electron emission.

Assvning the oscillator to be generating 05- cillations and taking a time when the righthand end 01' anode A is at a maximum .positive' potential and the lefthand end of anode A at a maximum negative potential electrons will take the paths E from the cathode to the anode. By suitably biasing the shield B to a suitable negative potential, the electrons will be electrostatically deflected taking a longer time to hit the anode than would be the case if the sleeve B were absent. By suitable choice of dimensions for the tube and electrodes, and by correct choice of potentials, and due to the kinetic energy of the electrons, matters can be arranged such that electrons will hit the righthand portion of anode A after the potential thereon has changed to a negative value. The electrons striking the anode, due to their kinetic energy, deliver their negative charge to the anode tending to drive the anode potential to a still more negative value. This continuesuntil the anode reverses its polarity and the operation is repeated on the other end of the anode and is a correct condition for oscillation generation. It is to be noted that the potential wave on the anode travels much more rapidly than the electrons through the anode-cathode space for the reason that the propagation of the wave along the anode approaches the velocity of light; whereas, electronic velocity within the tube is much slower.

Due to the relation between the tube voltages and frequency, the inherent operation of the tube is such that the time required for the electrons to travel from the cathode to the anode is substantially equal to the time of a half cycle of oscillation or to an integer times the period oionehalt cycle corresponding to the tuning of the anode circuit.

To stabilize the oscillator, I prefer, as shown in Figure 5 to make the antenna anode coiled at its center as shown at A By doing so, a higher circulating current will flow in the oscillating circuit and there will be, due to the coiling, a smaller percentage of energy radiated. Consequently, with increased flow of current in the circuit, increased stabilitywill follow. I

To increase the time of travel of electrons from the cathode to the anode, a magnetic field may be applied in a direction traversing the plane of the cathode and, as shown, in'the direction of lines M which indicate a magnetic field. Consequently, the electron travel ,will not only be de flected due to the electrostatic field indicated by lines L set up by sleeve B, but they will also be rotated or twisted about the anode before striking it thereby increasing still further the time of transit of electrons from cathode to anode.

In order to apply a magnetic field in a direction coaxial with the radiator A, a cylindrical solenoid G as shown diagrammatically in section in Figure 3, energized by suitable source of ener y K may be provided. As indicated, the cathode may be energized through a suitable source of alternating potential I and the cylindrical sleeve B may be biased by a source of potential J.

Modulating energy may be introduced in the.

form of variable anode potentials by means of an amplifier K and 'a suitable transformer P. It desired, the modulating apparatus may be placed in one or the leads from source H to the magnetic field mea ns G. Or, modulating energy for example,,,inthe iorm oi keyed alternating energy rather than complex currents may be introduced as shown in Figure 4 to vary the bias of sleeve B, the introduction taking place through a transformer P inserted in the biasing lead for the sleeve B.

The oscillations generated may be directionally transmitted by placing a parabolic reflector R an odd number of quarter wave lengths .and pgeterably one-quarter wave length behind ano e A. v 0i. course, if desired, taps could be placed symmetrically about the center of the anode A for supplying a transmission line which in turn would guide the modulated waves generated to any distant point desired.

Other ways of modulating the short waves generated by the apparatus will readily suggest themselves to one skilled in the art. Thus, for example, by placing spaced radiators near the anode A and alternately tuningv one of the other, propagation may be directed towards and away from a receiving station depending upon which of the spaced radiators. is tuned.

Having thus described my invention, what I claim is:

1. The method of generating electrical oscillations with an electron discharge device having a radiating anode having a .length substantially equal to an odd multiple of one-half the length of the generated oscillation and a cathode located between the ends of said anode, which includes, electrostatically lengthening the path taken by electrons traveling ,irom the cathode to the anode.

2. The method-of generating electrical oscillations with an electron discharge device having an anode and a cathode intermediate the ends of said anode, which includes, electrostatically lengthening the path taken by electrons traveling from the cathode to the anode and decreasing the anode potential at points along the anode as the electrons are about to strike it.

3. The method of generating oscillations in an electron discharge device having a rectilinear anode having a length substantially equal to an odd multiple of one-half the length 01 the generated oscillation and a cathode centrally located with respect to said anode and intermediate its ends, which includes electrostatically and magnetically lengthening the path 01' electron travel from the cathode to the anode.

4. The method of generating oscillations with an. electron discharge device oscillator having an anode and a cathode intermediate the ends of said anode, said anode having a potential applied thereto, which includes deflecting electrostatically, electrons leaving the cathode for the anode, magnetically twisting said electrons about the anode as they travel through the cathode anode space, and decreasing the anode potential at points along the anode as the electrons are about to strike it.

5. An electron discharge device having, in combination, an anode, a cathode within the length and intermediate the ends of said anode, and, a shield surrounding a portion'ot said anode tor causing electrons to take a relatively long path from the cathode to the anode.

6. An electron discharge device having, in combination, an anode, approximately one-half wave length long coiled at its center, a cathode, and, a shield adjacent the anode for causing electrons to take a relatively long path from the cathode to the anode. I f

'1. An electron discharge device having, in

combination, an anode arranged to radiate elecv 8. An electron discharge device having, in combination, an anode in the form of a radiator approximately one-half wave length long coiled at'its center, a sleeve about a portion of the anode, and a cathode.

9. An electron discharge device having, in combination, an anode in the form of a radiator coiled intermediate its ends, means for supplying anode potential at the mid-point thereof, a cylindrical sleeve about the central coiled portion of the anode, and a cathode.

10. An electron discharge device having, in combination, an anode in the form of a radiator approximately one-half wave length long coiled at its center, means for supplying anode potential at the mid-point thereof, a cylindrical sleeve about the central portion of the anode, and a cathode.

11. An electron discharge device having, in

' combination, a linear anode, a cylindrical sleeve coaxial with and about a portion of the anode and intermediate the ends of said anode, and a cathode disposed within the length of said sleeve in a plane traversing the axis of the sleeve and anode.

12. An electron discharge device having, in combination, a linear anode approximately onehalf wave length long coiled at its center, a cylindrical sleeve coaxial with and about a portion of the anode, and a cathode disposed in a plane traversing the axis of the sleeve'and anode.

13. An electron discharge device having, in combination, a linear anode, a cylindrical sleeve coaxial with and about a portion of the anode intermediate the ends of said anode, and a cathode disposed within the length of said sleeve in a plane perpendicular t the axis of the sleeve and anode.

14. An electron discharge device having, in combination, a linear anode approximately onehalf Wave length long coiled at its center, a cylindrical sleeve coaxial with and about a portion of the anode, and a cathode disposed in a plane perpendicular to the axis of the sleeve and anode.

15. An oscillation generator comprising an anode approximately one-half wave length long coiled at its center, a cathode, and a member having a potential applied thereto for deflecting electrons from the cathode towards the. anode in a path relatively longer than that which would be taken with the sleeve absent, whereby oscillations are set up in the anode,- and means for modulating the oscillations so set up.

16. In an electrical signaling system an electron discharge device having an anode'approximately one-half wave length long coiled intermediate its ends, a cathode, and a sleeve about the anode having a potential applied thereto for making electrons travel a relatively longer path from the cathode to the anode whereby oscillations are set up in the anode, means for modulating the oscillation set up, and means for directionally transmitting the electromagnetic wave propagated from the anode. 17. In combination, an electron discharge device having an anode aproximately one-half wave length long coiled at its center, a cathode, a sleeve having a suitable potential applied thereto for deflecting electrons traveling from' the cathode to the anode, and means for subjecting the electrons traveling from the cathode to the anode to a magnetic field. I

18. An electron discharge device having a linear anode approximately one-half wave length long, a cathode, a sleeve intermediate the ends of the anode and having a suitable potential applied thereto for electrostatically deflecting electrons traveling from the cathode towards the anode, said anode and sleeve being arranged coaxially, said cathode being disposed in a plane traversing the axis of said anode and sleeve, and means for applying a magnetic field to the elections in a direction traversing the plane of the cathode.

19. An oscillator comprising an electron dis charge device having a radiating anode approximately one-half wave length long coiled at its center, a cathode in a plane perpendicular to theaxis of the anode, a sleeve about a midportion of the anode for electrostatically deflecting electrons traveling from the cathode towards the anode, and, means for applying a magnetic field to the electrons in a direction parallel with the axis of the anode and sleeve.

20. An oscillator comprising an electron discharge device having a linear radiating anode approximately one-half wave lengthlong, a cathode in a plane perpendicular to the axis of the anode, a sleeve about a mid-portion of the anode for electrostatically deflecting electrons traveling from the cathode towards the anode, means for applying a magnetic field to the electrons in a direction paralle1 to the axis of the anode and sleeve whereby oscillations are set up in said anode, and means for modulating said oscillations.

21. An oscillator comprising an electron discharge device having a radiating anode one-half wave length long coiled at its center, a cathode in a plane perpendicular to the axis of the anode and having a suitable potential applied thereto, a sleeve about a mid-portion of the anode for electrostatically deflecting electrons traveling from the cathode towards the anode, means for applying a magnetic field to the electrons in a direction parallel with the axis of the anode and sleeve whereby oscillations are set up in said anode, means for modulating said oscillations, and, means for directionally transmitting the electromagnetic waves set up by the oscillations in the anode.

22. An oscillator comprising an electron discharge device having a linear radiating anode approximately one-half wave length long, a cathode in a plane perpendicular to the axis of the anode. a sleeve about a mid-portion of the anode at a suitable potential relative to said anode and cathode ior electrostatically deflecting electrons traveling from the cathode towards the anode, means for. applying a magnetic field to the electrons in a direction parallel to the axis of the anode and sleeve whereby oscillations are set up in said anode.

23. An oscillator comprising an electron discharge device having a radiating anode one-half wave length long, a cathode .in a plane perpendicular to the axis of the anode, a sleeve about a mid-portion of the anode and having a suitable potential applied thereto for electrostatically deflecting electrons traveling from the cathode towards the anode, means for applying a magnetic field to the electrons in a direction parallel with the axis of the anode and sleeve whereby oscillations are set up in said anode, and means for directionally transmitting the electromagnetic waves set up by the oscillations in the anode.

24. An electron discharge device having, in combination, a linear anode, a cathode located between the ends of saidanode, andimperforate f trode, the method of generating oscillations which shielding means intermediate said anode and cathode.

25. In an electron discharge device oscillation generator, the combination with a straight linear anode approximately an odd multiple of a halt ing from said cathode to take a relatively long path from the cathode to the anode.

27. In an electron discharge device, the combination with an anode in the form of a rod, of a cathode intermediate the ends of said anode and surrounding at'leas't a portion thereof, and an imperforate shield located directly between said cathode and anode. I

28. In an electron discharge device oscillator having a cathode'and anode, the method of generating oscillations which includes propelling electrons from said cathode to portions of said anode only at times when the portions are sub-.

jected to a maximum anode potential, decreasing the anode potential of the portions as .the electrons arrive, and generating a magnetic field to deflect the path of electrons.

29. In an electron discharge device oscillator having a cathode and an anode, a method of generating oscillations which includes propelling electrons-from said cathode to portions of said anode only at times when the electrons are subjected to a maximum anode potential, and decreasing the anode potential of the portions as the electrons arrive.

30. The method of signalling in a system including an electron discharge device oscillator havingan anode,a cathode,and acontrol electrode, which includes generating oscillations by attracting electrons to portions of the anode and then decreasing the anode voltage on the portions as the electrons arrive, modulating the oscillatory energy so generated, and radiating the modulated energy.

31. The method of signalling in a system including an electron discharge device oscillator havingan anode,a cathode,and acontrol electrode, which includes generating oscillations by attracting electrons to portions of the anode and then decreasing the anode voltages on the portions as the electrons arrive, modulating the oscillatory energy so generated, and directionally radiating the modulated energy.

32. In an electron discharge device having an anode and a cathode, the method of generating oscillations which includes attracting electrons toward a fractional portion of the anode, and decreasing the voltage on that portion of the anode as the electrons arrive.

33. In an electron discharge device oscillator having an anode, a cathode and a control elecincludes attracting electrons to portions of the anode only at times when the portions of the anode are subjected to a maximum anode potential, and decreasing the anode potential on the portiors as electronsarrive.

34. An electron discharge device oscillator comprising an electron discharge device having ah anode'and a source of potential 101; said anode, and an anode circuit tuned to a frequency such that the time required for electrons to travel between a pair of electrodes of the device is substantially equal to the time of one-half cycle corresponding to the tuning of the anode oscillation circuit.

35. In an electron discharge device, an anode and a cathode and means for suitably energizing same, said anode and cathode having such dimensions that after electrons are attracted towards a portion of the anode, they arrivev at said anode portion when the anode voltage on said portion changes to a value less than the maximum applied voltage.

36. In an electron discharge device, an anode tuned to a multiple of a half wave length long,

a cathode and a control-electrode and means for suitably energizing same, said anode, cathode and control electrode having such dimensions that-the electrons attracted towards a portion of the anode arrive at that portion of the anode a time later when that portionof the anode is subjected to a substantially minimum potential.

37. In an electron discharge device, an anode tuned to a multiple of a half wave length, a cathode and a control electrode, andmeans for applying a potential on said anode and a bias on the control electrode such that only that portion of the anode which is subjected to maximum anode potential draws electrons thereto.

38. An electron discharge device oscillator comprising an anode tuned to a multiple of a halt wave length, a cathode and a' control electrode, means'for modulating the oscillations generated by the oscillator, and means for transmitting the modulated oscillations. I

39. In an electron discharge device oscillator, an anode tuned to a multiple of a halt wave length, a cathode and a control electrode, means for modulating the oscillations generated by the oscillator, and means for directionally propagatserves to control or aid in the control, as well as to receive the flow of electrons'and in which the time relations of the control eflect and receiving of the electrons are made correct for regenerative action by the time required for the electrons to travel from the cathode to the anode, which comprises attracting electrons in streams alternately to different parts of the anode.

41. An electron discharge device oscillator comprising an electron discharge device having an anode circuit tuned to a frequency such that the time required for electrons to travel between a pair of electrodes of the device is substantially equal to an integer times the period of one-half cycle corresponding to the tuning of the anode oscillation circuit.

- 42. An electron discharge device oscillator comprising an electron discharge device having an anode circuit tuned to a frequency such that the time required for electrons to travel between a cathode and an anode of the device is substanwave length, a cathode, and a control electrode intermediate said anode and cathode, and means for applying a potential to the anode and a negai tive bias to the control electrode such that on y that portion of the anode which is subjected to a maximum anode potential draws electrons from said cathode thereto.

44. In an electron discharge device, an anode structurally designed to be tuned to a multiple of a half wave length, a cathode, and a control electrode intermediate said anode and cathode, means for applying a suitable potential to said anode at the midpoint thereof, and means vfor applying a negative bias on the control electrode such that only that portion of the anode which is subjected to the maximum anode potential draws electrons thereto.

45. An electron discharge device oscillator comprising an electron discharge device having an anode, a cathode, and a source of potential for said anode, and an anode circuit tuned to a frequency such that the time required for electrons to travel between said cathode and the anode of the device is substantially equal to the time of one-half cycle corresponding to the tuning of the anode oscillation circuit.

GEORGE L. USSELMAN. 

